I have some dash gauges on my boat that either are non functional or are in poor shape. Can I buy any gauge package set to replace them? Just want to make sure I don't need Ranger specific stuff.

yeah just the trim guage needs to be a merc compatible

here is a good place to shop for em.

http://www.teleflexmarine.com/products/instrumentation/instrumentation/

http://faria-instruments.com/boxset.php

pick the guage pkg you want then do an ebay search, lots of sets on there for cheap.